Freshwater ecosystems are the largest natural source of methane in the world, most of it derived from the partial consumption of terrestrial-derived carbon (C) sources. The main drivers of this C breakdown and greenhouse gas emissions (GHG) are microbes, including bacteria, archaea, and fungi. They are particularly important as forming the gut microbiota of aquatic detritivores, whose diet depends entirely on terrestrial C as energy source. As temperatures rise, metabolism in animals increases to compensate for higher respiration costs, enhancing consumption of carbon (C) relative to other nutrients. Thus, animals are expected to produce even more GHG in a positive feedback loop that reinforces climate warming. However, the extent to which increase in temperature can affect animal GHG emissions through increase in metabolism remains unknown. Along with changes in temperature, microbial communities will likely change their function and composition in face of rises in temperature. The proposed project sets out to elucidate how the increase in temperature affects the gut microbiota composition and function in invertebrates who are responsible for the breakdown of large amounts of C in Arctic ecosystems. GutChange bridges a gap between molecular ecology and ecosystem ecology, improves the understanding of aquatic-terrestrial linkages in the Arctic, and sets the foundation for the integration of functional-meta-omics into biodiversity and ecosystem functioning studies. This project offers a highly relevant study system around terrestrial-aquatic linkages and C cycles in Arctic freshwater ecosystems.